fix(snapshots): persist lastConfirmedAt into snapshot metadata upon pull confirmation

Record lastConfirmedAt in snapshot metadata when a source is confirmed (200 or 304). This ensures git-committed snapshot metadata reflects when sources like wiki.gg were successfully pulled even when page HTML did not change, avoiding false pull overdue notices on downstream builds like GitHub Pages.

test/refresh.test.ts

@@ -173,6 +173,7 @@ describe("a normal cycle", () => {
     const snapshot = await store.read("genshin-game8-events");
     expect(snapshot?.html).toBe("<html><event></event></html>");
     expect(snapshot?.meta.contentChangedAt).toBe("2026-08-01T00:00:00.000Z");
+    expect(snapshot?.meta.lastConfirmedAt).toBe(NOW.toISOString());
     expect(snapshot?.state.lastConfirmedAt).toBe(NOW.toISOString());
   });
 

test/snapshots.test.ts

@@ -385,16 +385,28 @@ describe("the six-hour floor", () => {
     expect(state.lastConfirmedAt).toBe(T1);
   });
 
-  test("check bookkeeping lives outside the committed metadata", async () => {
+  test("failed check bookkeeping lives in state without modifying meta", async () => {
     await save("<html>one</html>", T0);
     const before = await Bun.file(store.metaPath("genshin-game8-events")).text();
+    await store.recordCheck("genshin-game8-events", {
+      at: T1,
+      status: 503,
+      ok: false,
+    });
+    const after = await Bun.file(store.metaPath("genshin-game8-events")).text();
+    expect(after).toBe(before);
+  });
+
+  test("successful confirmation updates lastConfirmedAt in metadata", async () => {
+    await save("<html>one</html>", T0);
     await store.recordCheck("genshin-game8-events", {
       at: T1,
       status: 304,
       ok: true,
     });
-    const after = await Bun.file(store.metaPath("genshin-game8-events")).text();
-    expect(after).toBe(before);
+    const meta = await store.readMeta("genshin-game8-events");
+    expect(meta?.lastConfirmedAt).toBe(T1);
+    expect(meta?.contentChangedAt).toBe(T0);
   });
 });